Cartilage Imaging Research Articles

No pressure, no diamonds? - Static vs. dynamic compressive in-situ loading to evaluate human articular cartilage functionality by functional MRI

Biomechanical Magnetic Resonance Imaging (MRI) of articular cartilage, i.e. its imaging under loading, is a promising diagnostic tool to assess the tissue's functionality in health and disease. This study aimed to assess the response to static and dynamic loading of histologically intact cartilage samples by functional MRI and pressure-controlled in-situ loading. To this end, 47 cartilage samples were obtained from the medial femoral condyles of total knee arthroplasties (from 24 patients), prepared to standard thickness, and placed in a standard knee joint in a pressure-controlled whole knee-joint compressive loading device. Cartilage samples' responses to static (i.e. constant), dynamic (i.e. alternating), and no loading, i.e. free-swelling conditions, were assessed before (δ0), and after 30 min (δ1) and 60 min (δ2) of loading using serial T1ρ maps acquired on a 3.0T clinical MRI scanner (Achieva, Philips). Alongside texture features, relative changes in T1ρ (Δ1, Δ2) were determined for the upper and lower sample halves and the entire sample, analyzed using appropriate statistical tests, and referenced to histological (Mankin scoring) and biomechanical reference measures (tangent stiffness).Histological, biomechanical, and T1ρ sample characteristics at δ0 were relatively homogenous in all samples. In response to loading, relative increases in T1ρ were strong and significant after dynamic loading (Δ1 = 10.3 ± 17.0%, Δ2 = 21.6 ± 21.8%, p = 0.002), while relative increases in T1ρ after static loading and in controls were moderate and not significant. Generally, texture features did not demonstrate clear loading-related associations underlying the spatial relationships of T1ρ.When realizing the clinical translation, this in-situ study suggests that serial T1ρ mapping is best combined with dynamic loading to assess cartilage functionality in humans based on advanced MRI techniques.

Treatment of Patellofemoral Chondral Lesions Using Microfractures Associated with a Chitosan Scaffold: Mid-Term Clinical and Radiological Results.

To assess the clinical and radiological results of patellofemoral osteochondral lesions treated with microfractures associated with a chitosan scaffold. A retrospective observational analytical study was performed. Fifteen patients with full-thickness patellofemoral osteochondral lesions were included. Quantity and quality of the reparation cartilage was assessed with the MOCART 2.0 score on a postoperative magnetic resonance imaging (MRI), and clinical outcomes were evaluated with pre- and postoperative Kujala score tests. Shapiro-Wilk test for normality was applied as well as Wilcoxon's signed rank test and Kruskal-Wallis H test for clinical scores within subjects and patella versus trochlea subgroups comparisons. Analysis of variance test was used for imaging subgroups comparison, with P < 0.05 defined as statistical significance. Mean follow-up was 33.36 months (range 24-60 months). Postoperative Kujala scores improved an average of 19 points compared with the preoperative state (SE = 17.6; P < 0.001). No statistical difference was found through the clinical location assessment (P = 0.756), as well as the cartilage imaging assessment (P = 0.756). The mean MOCART 2.0 scale was 67.67 (range 50-85). Treating full-thickness patellofemoral osteochondral lesions with microfractures associated with a chitosan scaffold proved to be effective regarding defect filling and symptomatic improvement.

Quantitative Evaluation of Pubic Symphysis in Late Pregnancy Using T2* Mapping

Background: T2* mapping is a reliable tool in articular cartilage imaging. It has been widely used to evaluate the degeneration of knee joint and intervertebral discs. Degenerative joint disease of pubic symphysis is the primary cause of groin pain during late pregnancy. Objectives: To evaluate the alterations of pubic symphyseal cartilage during late pregnancy using T2* mapping. Patients and Methods: Sixty-one first-pregnancy women, 48 second-pregnancy women and 64 nulliparous women were enrolled in this case-control study. All subjects underwent MRI exam of the pubic symphysis on a 1.5T MR scanner, including T2* mapping sequence. Regions of interest (ROIs) were hand-drawn on T2* maps along the left and right side of the cartilage and anterior/middle/posterior sub-regions of each side. T2* values were analyzed and compared among the three groups using analysis of variance. The average pubic symphyseal width was measured. The correlation between pubic symphyseal width and T2* values of cartilage were analyzed using Pearson's correlation coefficient. Results: Compared with nulliparous women, T2* values increased significantly in late pregnancy in the left/right cartilage of pubic symphysis. The differences were mainly driven by the posterior sub-region; while, no differences were found between women during first and second pregnancies. The positive linear correlation between symphyseal width and mean T2* values of the cartilage was only seen in the group of women during first pregnancy, with no significant linear correlation in the other two groups. Conclusion: T2* mapping is a sensitive quantitative method capable of detecting changes in the pubic symphyseal cartilage related to pregnancy, and the T2* values increased significantly during late pregnancy.

Artificial Intelligence for Ultrasound Informative Image Selection of Metacarpal Head Cartilage. A Pilot Study.

Objectives: This study aims to develop an automatic deep-learning algorithm, which is based on Convolutional Neural Networks (CNNs), for ultrasound informative-image selection of hyaline cartilage at metacarpal head level. The algorithm performance and that of three beginner sonographers were compared with an expert assessment, which was considered the gold standard.Methods: The study was divided into two steps. In the first one, an automatic deep-learning algorithm for image selection was developed using 1,600 ultrasound (US) images of the metacarpal head cartilage (MHC) acquired in 40 healthy subjects using a very high-frequency probe (up to 22 MHz). The algorithm task was to identify US images defined informative as they show enough information to fulfill the Outcome Measure in Rheumatology US definition of healthy hyaline cartilage. The algorithm relied on VGG16 CNN, which was fine-tuned to classify US images in informative and non-informative ones. A repeated leave-four-subject out cross-validation was performed using the expert sonographer assessment as gold-standard. In the second step, the expert assessed the algorithm and the beginner sonographers' ability to obtain US informative images of the MHC.Results: The VGG16 CNN showed excellent performance in the first step, with a mean area (AUC) under the receiver operating characteristic curve, computed among the 10 models obtained from cross-validation, of 0.99 ± 0.01. The model that reached the best AUC on the testing set, which we named “MHC identifier 1,” was then evaluated by the expert sonographer. The agreement between the algorithm, and the expert sonographer was almost perfect [Cohen's kappa: 0.84 (95% confidence interval: 0.71–0.98)], whereas the agreement between the expert and the beginner sonographers using conventional assessment was moderate [Cohen's kappa: 0.63 (95% confidence interval: 0.49–0.76)]. The conventional obtainment of US images by beginner sonographers required 6.0 ± 1.0 min, whereas US videoclip acquisition by a beginner sonographer lasted only 2.0 ± 0.8 min.Conclusion: This study paves the way for the automatic identification of informative US images for assessing MHC. This may redefine the US reliability in the evaluation of MHC integrity, especially in terms of intrareader reliability and may support beginner sonographers during US training.

Biochemical MRI With dGEMRIC Corresponds to 3D-CT Based Impingement Location for Detection of Acetabular Cartilage Damage in FAI Patients.

Background:Anterior femoroacetabular impingement (FAI) is associated with labral tears and acetabular cartilage damage in athletic and young patients. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is an imaging method for detecting early damage to cartilage.Purpose:We evaluated the following questions: (1) What is the sensitivity and specificity of morphological magnetic resonance imaging (MRI) and dGEMRIC for detecting cartilage damage? Do the mean acetabular and femoral dGEMRIC indices differ between (2) superior acetabular clock positions with and without impingement and (3) between cam- and pincer-type FAI?Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:This was a retrospective comparative study of 21 hips (20 patients with symptomatic anterior FAI) without osteoarthritis on anteroposterior radiographs. Morphological MRI and dGEMRIC (3.0-T, 3-dimensional [3D] T1 maps, dual–flip angle technique) of the same hip joint were compared. Intraoperative acetabular cartilage damage was assessed in patients who underwent surgical treatment. Computed tomography (CT)–based 3D bone models of the same hip joint were used as the gold standard for the detection of impingement, and dGEMRIC indices and zones of morphologic damage were compared with the CT-based impingement zones.Results:Of the 21 hips, 10 had cam-type FAI and 8 had pincer-type FAI according to radiographs. The mean age was 30 ± 9 years (range, 17-48 years), 71% were female, and surgical treatment was performed in 52%. We found a significantly higher sensitivity (69%) for dGEMRIC compared with morphological MRI (42%) in the detection of cartilage damage (P < .001). The specificity of dGEMRIC was 83% and accuracy was 78%. The mean peripheral acetabular and femoral dGEMRIC indices for clock positions with impingement (485 ± 141 and 440 ± 121 ms) were significantly lower compared with clock positions without impingement (596 ± 183 and 534 ± 129 ms) (P < .001). Hips with cam-type FAI had significantly lower acetabular dGEMRIC indices compared with hips with pincer-type FAI on the anterosuperior clock positions (1 to 3 o’clock) (P = .018).Conclusion:MRI with dGEMRIC was more sensitive than morphological MRI, and lower dGEMRIC values were found for clock positions with impingement as detected on 3D-CT. This could aid in patient-specific diagnosis of FAI, preoperative patient selection, and surgical decision making to identify patients with cartilage damage who are at risk for inferior outcomes after hip arthroscopy.

Acute Talar Cartilage Deformation in Those with and without Chronic Ankle Instability.

This study aimed 1) to determine whether talar cartilage deformation measured via ultrasonography (US) after standing and hopping loading protocols differs between chronic ankle instability (CAI) patients and healthy controls and 2) to determine whether the US measurement of cartilage deformation reflects viscoelasticity between standing and hopping protocols. A total of 30 CAI and 30 controls participated. After a 60-min off-loading period, US images of the talar cartilage were acquired before and after static (2-min single-leg standing) and dynamic (60 single-leg forward hops) loading conditions. We calculated cartilage deformation by assessing the change in average thickness (mm) for overall, medial, and lateral talar cartilage. The independent variables include time (Pre60 and postloading), condition (standing and dynamic loading), and group (CAI and control). A three-way mixed-model repeated-measures ANCOVA and appropriate post hoc tests were used to compare cartilage deformation between the groups after static and dynamic loading. After the static loading condition, those with CAI had greater talar cartilage deformation compared with healthy individuals for overall (-10.87% vs -6.84%, P = 0.032) and medial (-12.98% vs -5.80%, P = 0.006) talar cartilage. Similarly, the CAI group had greater deformation relative to the control group for overall (-8.59% vs -3.46%, P = 0.038) and medial (-8.51% vs -3.31%, P = 0.043) talar cartilage after the dynamic loading condition. In the combined cohort, cartilage deformation was greater after static loading compared with dynamic in overall (-8.85% vs -6.03%, P = 0.003), medial (-9.38% vs -5.91%, P = 0.043), and lateral (-7.90% vs -5.65%, P = 0.009) cartilage. US is capable of detecting differences in cartilage deformation between those with CAI and uninjured controls after standardized physiologic loads. Across both groups, our results demonstrate that static loading results in greater cartilage deformation compared with dynamic loading.

DGEMRIC in the Assessment of Pre-Morphological Cartilage Degeneration in Rheumatic Disease: Rheumatoid Arthritis vs. Psoriatic Arthritis.

Background: Even though cartilage loss is a known feature of psoriatic (PsA) and rheumatoid arthritis (RA), research is sparse on its role in the pathogenesis of PsA, its potential use for disease monitoring and for differentiation from RA. We therefore assessed the use of delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) to evaluate biochemical cartilage changes in metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints in PsA patients and compared these to RA patients. Materials and Methods: A total of 17 patients with active PsA and 20 patients with active RA were evaluated by high-resolution 3 Tesla dGEMRIC using a dedicated 16-channel hand coil. Images were analyzed by two independent raters for dGEMRIC indices and joint space width (JSW) at MCP and PIP joint levels. Results: No significant differences of dGEMRIC values could be found between both study populations (PsA 472.25 ms, RA 461.11 ms; p = 0.763). In all RA and most PsA patients, PIP joints showed significantly lower dGEMRIC indices than MCP joints (RA: D2: p = 0.009, D3: p = 0.008, D4: p = 0.002, D5: p = 0.002; PsA: D3: p = 0.001, D4: p = 0.004). Most joint spaces had similar widths in both disease entities and no significant differences were found. Conclusions: As evaluated by dGEMRIC, the molecular composition of the MCP and PIP joint cartilage of PsA patients is similar to that of RA patients, demonstrating the scientific and clinical feasibility of compositional magnetic resonance (MR) imaging in these disease entities. Patterns and severity of compositional cartilage degradation of the finger joints may therefore be assessed beyond mere morphology in PsA and RA patients.

Deep learning enables the automation of grading histological tissue engineered cartilage images for quality control standardization

To automate the grading of histological images of engineered cartilage tissues using deep learning. Cartilaginous tissues were engineered from various cell sources. Safranin O and fast green stained histological images of the tissues were graded for chondrogenic quality according to the Modified Bern Score, which ranks images on a scale from zero to six according to the intensity of staining and cell morphology. The whole images were tiled, and the tiles were graded by two experts and grouped into four categories with the following grades: 0, 1-2, 3-4, and 5-6. Deep learning was used to train models to classify images into these histological score groups. Finally, the tile grades per donor were averaged. The root mean square errors (RMSEs) were calculated between each user and the model. Transfer learning using a pretrained DenseNet model was selected. The RMSEs of the model predictions and 95% confidence intervals were 0.49 (0.37, 0.61) and 0.78 (0.57, 0.99) for each user, which was in the same range as the inter-user RMSE of 0.71 (0.51, 0.93). Using supervised deep learning, we could automate the scoring of histological images of engineered cartilage and achieve results with errors comparable to inter-user error. Thus, the model could enable the automation and standardization of assessments currently used for experimental studies as well as release criteria that ensure the quality of manufactured clinical grafts and compliance with regulatory requirements.

A study on spectrum of MRI findings in traumatic knee

MRI has emerged as an excellent modality for imaging of ligaments, cartilage, menisci and other structures around the knee joint. This is due to the combination of multiplanar capability and superior soft tissue characterization. This modality has superseded already available modalities like radiograph and CT, over last two decades. A prospective study consisting of 50 patients with traumatic knee joint was undertaken to study the spectrum of MRI findings in all consecutive cases of knee trauma referred from orthopedic OPD. Out of 20 patients with isolated medial meniscus tear, the posterior horn was commonest site of involvement occurring in 11 patients (55%) and the predominant type of tear was horizontal and oblique that occurred in 7 patients each (35%). Grade III tear were the commonest seen in 12 patient (60%) followed by grade II in 8 patients (40%).

Internal dosimetry of [99m Tc]NTP15-5 radiotracer for cartilage imaging in preclinical and clinical models using the GATE Monte Carlo platform.

This study aims to perform dosimetry for [99m Tc]NTP15-5 radiotracer used in imaging of articular cartilage in rabbits and humans. The radiotracer (covered by a world patent WO 01/00621 A1) has been proposed in the previous years for the study of cartilage in osteoarthritis diseases. A sensitive imaging approach is essential to quantify osteoarthritis progression and monitor response to new therapies. [99m Tc]NTP15-5 binds to cartilage proteoglycans whose decreased content is associated to a loss of biomedical function of cartilage. We have implemented the whole dosimetry study concerning this new radiotracer for rabbits and humans using the GATE Monte Carlo platform. Absorbed doses to critical organs are determined using the MIRD formalism. Biodistribution data are obtained by organ sampling, measuring the activity in organs for three rabbits sacrificed at various times postadministration, and by SPECT/CT imaging at different times after injection. Most important sources are cartilages (in knees and intervertebral discs), due to localization together with the liver and kidneys due to excretion of the agent. S-values are calculated from rabbit's CT scan and human CT scan using the GATE v8.0 Monte Carlo platform. Cumulated activity in humans is extrapolated from animals using the %kg-dose/g method. Particular attention is given to dose calculation in bones, bone marrow and organs at risk. The dosimetry performed in rabbits shows highest absorbed doses for liver and kidneys with respectively 22.5 and 43.8µGy per MBq of injected activity. In humans, we found absorbed doses for a maximum injected activity of 15MBq/kg, that is, 1050MBq for an adult of 70kgs of 9.03mGy for kidneys and 4.16mGy for knee cartilages. Effective dose is 2.69µSv/MBq. The dosimetry profile of [99m Tc]NTP15-5 in the context of preclinical trials is of major importance in order to make sure that organs at risk are not overexposed. GATE provides all the capability needed to calculate dose profiles for internal dosimetry. The extrapolation of the dose for a human model is a first step towards clinical trials.

Higher aggrecan 1-F21 epitope concentration in synovial fluid early after anterior cruciate ligament injury is associated with worse knee cartilage quality assessed by gadolinium enhanced magnetic resonance imaging 20\u2009years later

BackgroundTo investigate if cartilage related biomarkers in synovial fluid are associated with knee cartilage status 20 years after an anterior cruciate ligament (ACL) injury.MethodsWe studied 25 patients with a complete ACL rupture without subsequent ACL reconstruction or radiographic knee OA. All had a delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) 20 years after the ACL injury, using the T1 transverse relaxation time in the presence of gadolinium (T1Gd) which estimates the concentration of glycosaminoglycans in hyaline cartilage. Synovial fluid samples were aspirated acutely (between 0 and 18 days) and during 1 to 5 follow up visits between 0.5 and 7.5 years after injury. We quantified synovial fluid concentrations of aggrecan (epitopes 1-F21 and ARGS), cartilage oligomeric matrix protein, matrix metalloproteinase-3 and tissue inhibitor of metalloproteinase-1 by immunoassays, and sulfated glycosaminoglycans by Alcian blue precipitation. Western blot was used for qualitative analyses of aggrecan fragments in synovial fluid and cartilage samples.ResultsWestern blot indicated that the 1-F21 epitope was located within the chondroitin sulfate 2 region of aggrecan. Linear regression analyses (adjusted for age, sex, body mass index and time between injury and sampling) showed that acute higher synovial fluid 1-F21-aggrecan concentrations were associated with shorter T1Gd values 20 years after injury, i.e. inferior cartilage quality (standardized effects between − 0.67 and − 1.0). No other statistically significant association was found between molecular biomarkers and T1Gd values.ConclusionHigher acute synovial fluid 1-F21-aggrecan concentrations in ACL injured patients, who managed to cope without ACL reconstruction and were without radiographic knee OA, were associated with inferior knee cartilage quality assessed by dGEMRIC 20 years after injury.

Convolutional neuronal networks combined with X-ray phase-contrast imaging for a fast and observer-independent discrimination of cartilage and liver diseases stages

We applied transfer learning using Convolutional Neuronal Networks to high resolution X-ray phase contrast computed tomography datasets and tested the potential of the systems to accurately classify Computed Tomography images of different stages of two diseases, i.e. osteoarthritis and liver fibrosis. The purpose is to identify a time-effective and observer-independent methodology to identify pathological conditions. Propagation-based X-ray phase contrast imaging WAS used with polychromatic X-rays to obtain a 3D visualization of 4 human cartilage plugs and 6 rat liver samples with a voxel size of 0.7 × 0.7 × 0.7 µm3 and 2.2 × 2.2 × 2.2 µm3, respectively. Images with a size of 224 × 224 pixels are used to train three pre-trained convolutional neuronal networks for data classification, which are the VGG16, the Inception V3, and the Xception networks. We evaluated the performance of the three systems in terms of classification accuracy and studied the effect of the variation of the number of inputs, training images and of iterations. The VGG16 network provides the highest classification accuracy when the training and the validation-test of the network are performed using data from the same samples for both the cartilage (99.8%) and the liver (95.5%) datasets. The Inception V3 and Xception networks achieve an accuracy of 84.7% (43.1%) and of 72.6% (53.7%), respectively, for the cartilage (liver) images. By using data from different samples for the training and validation-test processes, the Xception network provided the highest test accuracy for the cartilage dataset (75.7%), while for the liver dataset the VGG16 network gave the best results (75.4%). By using convolutional neuronal networks we show that it is possible to classify large datasets of biomedical images in less than 25 min on a 8 CPU processor machine providing a precise, robust, fast and observer-independent method for the discrimination/classification of different stages of osteoarthritis and liver diseases.

Potential influence from lower limb preference and 1-RM on cartilage thickness

PurposeThe aims of this study were to assess the potential retrospective relationship between limb preference and cartilage thickness, and to determine the association between measures of strength using 1-RM tests and cartilage thickness.MethodsCross-sectional retrospective design was employed. Limb preference and injury history were collected using the Waterloo Inventory followed by femoral cartilage imaging using ultrasound. 15 apparently healthy participants (11 males and four females) without musculoskeletal or neurological diseases volunteered for the study. After collection of anthropometric measures, warm-up and familiarization, participants performed 1-RM for back half-squat on a Smith machine. Ultrasound images were digitized to determine bilateral differences and femoral cartilage thickness.ResultsSignificant moderate association between the existence of a prior injury and bilateral differences in cartilage thickness (&lt;i&gt;r&lt;/i&gt; = -0.63, &lt;i&gt;p&lt;/i&gt; &lt; 0.01), in favor of the preferred limb was observed. Significant moderate association between the 1-RM, as percentage of body mass, and the mean cartilage thickness between limb (&lt;i&gt;r&lt;/i&gt; = 0.58, &lt;i&gt;p&lt;/i&gt; = 0.049).ConclusionsBilateral differences in cartilage thickness are not associated with limb preference but depend on the history of lower limb injuries. The relative load lifted during a 1-RM half-squat is associated with thicker femoral cartilages, which suggests that relative strength is an important measure of cartilage health.

Cartilage Degradation in Psoriatic Arthritis Is Associated With Increased Synovial Perfusion as Detected by Magnetic Resonance Imaging.

Objective: Even though cartilage loss is a known feature of psoriatic arthritis (PsA), research is sparse on its role in the pathogenesis of PsA and its potential use for disease detection and monitoring. Using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and dynamic contrast-enhanced MRI (DCE MRI), research has shown that early cartilage loss is strongly associated with synovial inflammation in rheumatoid arthritis (RA). The aim of this study was to determine if acute inflammation is associated with early cartilage loss in small finger joints of patients with PsA.Methods: Metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of 17 patients with active PsA were evaluated by high-resolution 3 Tesla dGEMRIC and DCE MRI using a dedicated 16-channel hand coil. Semi-quantitative and quantitative perfusion parameters were calculated. Images were analyzed by two independent raters for dGEMRIC indices, PsA MRI scores (PsAMRIS), total cartilage thickness (TCT), and joint space width (JSW).Results: We found significant negative correlations between perfusion parameters (except Kep) and dGEMRIC indices, with the highest value at the MCP joints (KTrans: τ = −0.54, p = 0.01; Kep: τ = −0.02, p = 0.90; IAUC: τ = −0.51, p = 0.015; Initial Slope: τ = −0.54, p = 0.01; Peak: τ = −0.67, p = 0.002). Heterogeneous correlations were detected between perfusion parameters and both, total PsAMRIS and PsAMRIS synovitis sub-scores. No significant correlation was seen between any perfusion parameter and JSW and/or TCT.Conclusion: As examined by DCE MRI and dGEMRIC, there is a potential association between early cartilage loss and acute synovial inflammation in small finger joints of PsA patients.

Nanotechnology and osteoarthritis; part 1: Clinical landscape and opportunities for advanced diagnostics.

Osteoarthritis (OA) is a disease of the entire joint, often triggered by cartilage injury, mediated by a cascade of inflammatory pathways involving a complex interplay among metabolic, genetic, and enzymatic factors that alter the biochemical composition, microstructure, and biomechanical performance. Clinically, OA is characterized by degradation of the articular cartilage, thickening of the subchondral bone, inflammation of the synovium, and degeneration of ligaments that in aggregate reduce joint function and diminish quality of life. OA is the most prevalent joint disease, affecting 140 million people worldwide; these numbers are only expected to increase, concomitant with societal and financial burden of care. We present a two-part review encompassing the applications of nanotechnology to the diagnosis and treatment of OA. Herein, part 1 focuses on OA treatment options and advancements in nanotechnology for the diagnosis of OA and imaging of articular cartilage, while part 2 (10.1002/jor.24842) summarizes recent advances in drug delivery, tissue scaffolds, and gene therapy for the treatment of OA. Specifically, part 1 begins with a concise review of the clinical landscape of OA, along with current diagnosis and treatments. We next review nanoparticle contrast agents for minimally invasive detection, diagnosis, and monitoring of OA via magnetic resonace imaging, computed tomography, and photoacoustic imaging techniques as well as for probes for cell tracking. We conclude by identifying opportunities for nanomedicine advances, and future prospects for imaging and diagnostics.

Imaging of the articular cartilage repair

Postoperative imaging is necessary for assessing the technical success of the procedure and state of the cartilage healing, as well as for identifying potential complication. A plenty of radiological methods are available today in assessing the articular cartilage: radiography, computed tomography and thomositesis, ultrasonography and magnetic resonance. Radiography is the most used radiological modality but with high limitations in evaluation of the articular cartilage repair. Computed tomography and tomosynthesis are useful only after intraarticular contrast media injection (arthrography) and offer the evaluation of the cartilage surface but with the harmful influence of ionizing radiation. Magnetic resonance (MR) imaging provides non-invasive assessment of the entire joint including evaluation of the cartilage changes and lesions as well as the assessment of the repair site and all other joint tissues. Using compositional MR imaging of cartilage we may get information about its molecular status, specifically in regard to its collagen and glycosaminoglycan content. This article is a review of all imaging methods, in cartilage repair evaluation stressing novel imaging methods representing their advantages and limitations in cartilage repair evaluation.

Magnetic Resonance Imaging Features of Early Knee Cartilage Injury in Athletes and Its Significance in Diagnosis

Objective: The objective is to study the application and significance of magnetic resonance imaging (MRI) in the diagnosis of early knee joint cartilage injury in athletes, so as to provide corresponding rehabilitation training. Method: The imaging manifestations of T2 mapping of patellar cartilage in athletes and healthy volunteers are studied. 32 national professional athletes are included. The imaging characteristics of T2 mapping pseudocolor images of normal patellar cartilage are analyzed. The image characteristics of early patellar cartilage injury in T2 mapping pseudocolor images are analyzed, and the comparison of cartilage injury between athletes and ordinary people, as well as the injury of left and right knee cartilage of athletes are obtained. Results: The average value of T2 (T2av) of right patellar cartilage of athletes is higher than that of left patellar cartilage, and there are significant differences. The average T2av of right patellar cartilage is slightly higher than that of left patellar cartilage in healthy volunteers, with no significant differences. With the increase of training years, the color scale of patellar cartilage gradually increases, from the surface to the deep layer. In addition, the damage is aggravated, the blue range is reduced, the green range is expanded, and some yellow areas appear, which are more mixed. The lateral area and deviation to lateral area of right patellar cartilage are more obvious, and the T2 value is increased. Conclusion: T2 mapping can reflect the early injury of articular cartilage sensitively, intuitively and quantitatively. Before the morphological changes, the changes of biochemical structure of degenerative articular cartilage can be found by T2 mapping, which can provide theoretical support for the detection of early injury of knee cartilage in athletes.

Gadolinium-hyaluronic acid nanoparticles as an efficient and safe magnetic resonance imaging contrast agent for articular cartilage injury detection

Accurate detection of cartilage injuries is critical for their proper treatment because these injuries lack the self-healing ability and lead to joint dysfunction. However, the low longitudinal T1 relaxivity (r1) and non-specificity of contrast agents (such as gadolinium(III)-diethylenetriamine-pentaacetic acid (Gd-DTPA)) significantly limit the efficiency of clinical magnetic resonance imaging (MRI) applications. To overcome these drawbacks, we integrated hyaluronic acid (HA) with Gd to synthesize a Gd-DTPA-HA composite, which was subsequently freeze-dried to produce nanoparticles (NPs). The resultant Gd-HA NPs demonstrated a greater r1 value (12.51 mM−1 s−1) compared with the bulk Gd-DTPA-HA (8.37 mM−1 s−1) and clinically used Gd-DTPA (3.88 mM−1 s−1). Moreover, the high affinity of HA to the cartilage allowed these NPs to penetrate deeper beyond the cartilage surface. As a result, Gd-HA NPs considerably increased the quality of cartilage and lesion MR images via their intra-articular injection in vivo. Specifically, 2 h after NP administration, the signal-to-noise ratio at the injured cartilage site was 2.3 times greater than the value measured before the injection. In addition, Gd-HA NPs exhibited good biosafety properties due to the absence of adverse effects in the blood or on the main organs. It was also showed that Gd NPs were first metabolized by the kidney and liver and then excreted from the body with urine. Thus, Gd-HA NPs can potentially serve as an efficient MRI contrast agent for improved detection of cartilage injuries.

Is There a Role for Cartilage Imaging in Athletes?

This article reviews implications for cartilage imaging in athletes in the setting of (1) acute chondral injury diagnosis, (2) evaluation and follow-up of conservative and surgical therapy, and (3) evaluation of cartilage as a surrogate for meniscal function and joint stability. Focal knee cartilage defects are common in athletic populations. Athletes with articular cartilage injury may initially be able to return to sport with conservative therapy; however, a reduction of athletic ability and progression to osteoarthritis is expected in athletes with untreated severe chondral injury. For diagnostic and pre- and postsurgical evaluation purposes, morphological magnetic resonance (MR) assessment of the articular cartilage with high-resolution protocols is crucial. Although not widely implemented for clinical use, compositional MR techniques have great potential for monitoring the development and progression of biochemical and microstructural changes in cartilage extracellular matrix before gross morphological changes occur.

Proteoglycan loss in the articular cartilage is associated with severity of joint inflammation in psoriatic arthritis\u2014a compositional magnetic resonance imaging study

BackgroundEven though cartilage loss is a known feature of psoriatic arthritis (PsA), little is known about its role in the pathogenesis of PsA. Using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) as a non-invasive marker of the tissue’s proteoglycan content, such early (i.e., pre-morphological) changes have been associated with inflammation in rheumatoid arthritis (RA). Yet, this association has not been studied before in PsA.MethodsThe metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of 17 patients with active PsA were evaluated by high-resolution clinical standard morphological and dGEMRIC sequences using a 3T MRI scanner (Magnetom Skyra, Siemens) and a dedicated 16-channel hand coil. Images were analyzed by two independent raters for dGEMRIC indices, PsA MRI scores (PsAMRIS), and total cartilage thickness (TCT). Kendall tau correlation coefficients (τ) were calculated.ResultsWe found significant negative correlations between dGEMRIC indices and total PsAMRIS (τ = − 0.5, p = 0.012), synovitis (τ = − 0.56, p = 0.006), flexor tenosynovitis (τ = − 0.4, p = 0.049), and periarticular inflammation (τ = − 0.72, p < 0.001). Significant positive correlations were found between TCT and dGEMRIC indices at all joint levels (τ = 0.43, p < 0.001). No significant correlations were determined between dGEMRIC indices and bone erosion, bone edema, or bone proliferation.ConclusionIn PsA, proteoglycan loss as assessed by dGEMRIC is associated with periarticular inflammation, synovitis, and flexor tenosynovitis, but not with bone erosion or proliferation. Thereby, these findings contribute to in vivo concepts of the disease’s pathophysiology. Beyond morphology, advanced MRI techniques may be used to assess cartilage composition in PsA and to identify early changes in the cartilage as an imaging biomarker with potential application in detection, monitoring, and prediction of outcomes of PsA.Trial registration2014123117, December 2014.